DE 
FR
Doppeldoline im Schäll
"Double Doline"
Karstlehrpfad Kaltbrunnental-Brislachallmet
DE FR
Doppeldoline im Schäll
"Double Doline"
Karstlehrpfad Kaltbrunnental-Brislachallmet
Dolines
Dolines are common karst formations occurring in the shape of funnels, basins, or as shallow dents in the karst landscape. In the slavic languages ‘dolina’ is the word for valley and also for small closed cavities in the karst.
The diameter of dolines varies between just a few metres and 1500m, with depths of up to 300m. They may appear isolated or occupy whole fields or form in extended rows along the edges or breaks in the rocks.
How are dolines formed?
Dolines are formed in places where surface water seeps deep into the ground. These are weak spots in the rock formation, such as clefts, rock edges or breaks. The only exception to this rule is the collapse doline, which can be caused by the instability of the overlap of the underlying cavity.The two most important factors in the creation of dolines are precipitation (rain or snow) and the presence of soluble rock such as limestone, marble or dolomite.
Dolines formed through solution
They are formed when the rock under the soil is dissolved, thus enlarging an existing crack. Fine rock particles are washed away, and the resulting cavity fills up with soil from the surface. Flat indentations or basins are formed in this way.Subsidence dolines
These are formed by the slow downward movement of the surface. Erosion below ground dissolves and moves rocks. Rocks from further up move into the gap.
Alluvial dolines
These are a mixture of solution dolines and subsidence dolines. Here the cracks in the rocks (drainage paths) are large enough to carry surrounding loosened material away. This encourages the process of erosion (destruction, transport and deposit of rock) on the surface and below ground. The loose material at the top drops down, the rock below ground settles, and a funnel is formed.
Collapse dolines
They are usually the result of a single rapid event, caused by the closeness to the surface of hollow spaces. Such a cave-in can be triggered by a heavy weight, e.g. a tractor or a cow, or a roof that has become too heavy above an expanding cave and collapses. With luck this will open a new access to a cave.
Broschüre "Die Dolinen"
